What is the custom function(p,a,c,k,e,d) used for?

Question

I have seen a lot of websites with some function (p,a,c,k,e,d) in their JavaScript code. The different websites may have different bodies of this function, but

Answer 1

It's a function which decompresses compressed/obfuscated javascript code. Many JS libraries and scripts make use of it.

There are online tools where you can pack and unpack code via the browser, which use the function.